Capitalism encourages screwing over other people, being cutthroat in business, etc.
Communism encourages different faults, such as passivity, mob mentalities, and not taking responsibility.
Anarchism would discourage considering the effects of 2nd-order+ consequences.
The competition knob is but one knob among many. It's the one America happens to have at about an 8.5 (and one which I dislike greatly), but I don't think this problem is unique to capitalism.
Given the levels of consolidation we've seen over the past 30 years or so, I'd say that a lack of competition also contributes to unethical behavior. In fact, the consolidation pursued by many corporations is predicated on swallowing up even potential competitors in an effort to consolidate their dominant position.
I'd say that was unethical too.
We're drifting off topic, though. If Amazon heavily incentivizes bad behavior, should they be allowed to reap the rewards and discharge the blame? Absolutely not. They're culpable.
Despite the fact that managing this balance is fundamental to a capitalist society, it's extremely typical for the latter half of this balance to be ignored, for competition to be framed as an unmitigated positive, and for the Goodhart's Law side of it to be completely swept under the rug.
Culpability should be attributed both to the individual and to the system. Otherwise it's easy to construct systems that bypass responsibility. Like we see here.